172 S>/ii//i : Tlic Use of Maps in liofduy. 



to the facts, or convey the impression of what the object really 

 looks like by showin<;- it to others. The sketch and the photo- 

 graph, the rough chart and the map, are all means of illustrating- 

 what one wishes to convey. The map is a form of illustration 

 which has long- been used by the geologist, but has not been 

 valued at its true worth in other branches of natural history. 

 In Botany the small map showing the distribution of a natural 

 order has been in use for some time, but the use of large-scale 

 maps to show the features of a small area is comparatively 

 recent. The success of these has attracted attention to their 

 use as records of local natural history. Recent volumes of the 

 Naturalist contain several suggestions of this kind,* and the 

 present notes are mainly intended to be supplementary to the 

 extremely practical hints on map-records by Messrs. Cosmo 

 Johns and Alfred Harker in last year's volume. The former 

 author has suggested so many ways in which maps may be used 

 to record facts in natural histor}- that we need not tarry over 

 this side of the matter. 



One of the first points to be decided is the kind of map to use. 

 Those available for field-work are g^enerally known by some 

 name indicating the scale used to represent a mile ; the more 

 important are : — 



{a) 'Quarter-inch,' or 'four miles to one inch.' Here 

 each inch represents four horizontal miles, and the numerical 

 reduction is i : 253440 of actual length on the ground.! 



[b) ' Half-inch,' 'two niiles to one inch,' or i : 126720. 



(r) 'Inch,' one inch to one mile, or i : 63360 ; sheets 

 (12 X 18 miles) cost is. each. 



{ii) 'Six-inch,' 'six inches to one mile,' or i : 10500; sheets 

 (6x4 miles) 2s. 6d. , or quarter sheets (3 x 2 miles) is. 



{e) 'Twenty-five-inch,' or 'twenty-five-inches to one mile.' 

 The numerical reduction here is i : 2500 of actual length on the 

 g-round (this is the easiest numerical ratio to remember), and a 

 mile is actually 25.344 inches on the map. It is also useful to 

 remember that one square inch of this map approximately 

 represents one acre. 



The Ordnance Survey Departnu-nl pul)li.sli mai)s on all the 

 scales given above, except the half-inch, anil tlu-y are the best 

 maps obtainable in Hritain. Convenient maps on the quarter- 



* .Maps ami Kciuitls. Comiio Joliiis (Srplriiil) -f, k)05, j)]). jOu-jOj). 

 The Recording- of Localities. .Alfred Harker (November, 1905, p. 331). 



t The iiuinerical reduction should always be ^-ivi-n in the case of publica- 

 tion, as it is much more convenient for compai-ison with foreign maps than 

 tlie Eng-lish inch scale. 



Naturalist, 



